Some compounds of the aryl pyrazole family are known to possess excellent insecticidal activity. Within this family of compounds, Fipronil, 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinylpyrazole, has potent activity against insects and acarids. Fipronil binds to the gamma aminobutyric acid (GABA) receptors in the cell membranes of invertebrate neurons, functionally stabilizing the closed form of the channel, resulting in death of invertebrates. Fipronil has a chemical structure as shown herein below, as structure I:

5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole is an important intermediate used in the process for preparation of Fipronil and has the following chemical structure shown herein below, as structure (II):

Various synthetic routes are available for the preparation of aminopyrazole i.e., 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole.
These synthetic routes are accompanied with various drawbacks such as generation of large amounts of acidic effluent, several reaction steps, and difficulty in dealing with the waste acid, use of toxic reagents, low purity, and low yield of product. Therefore, there is a need for a simple process having minimum process steps, superior product quality, reasonable cost, and excellent synthetic route to achieve large-scale industrial production and which is environment friendly.
Thus, there is felt need for a process for preparing 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole (intermediate of Fipronil) in high yield in a simple, economical and environment friendly manner.